We studied cadmium toxicity in murine hepatocytes in vitro. Cadmium effects on intracellular free Ca2+ concentration ([Ca2+]i) were assayed, using a laser scanning confocal microscope with a fluorescent probe, Fluo-3/AM. The results showed that administration of cadmium chloride (CdCl2, 5, 10, 25 μM) resulted in a dose-dependent decrease of hepatocyte viability and an elevated aspartate aminotransfe rase (AST) activity in the culture medium (p<0.05 for 25 μM CdCl2 vs. control). Significant increases of lactate dehydrogenase (LDH) activities in 10 and 25 μM CdCl2-exposed groups were observed (p<0.05 and p<0.01, respectively). A greatly decreased albumin content and a more malondialdehyde (MDA) formation also occurred after CdCl2 treatment. The Ca2+ concentrations in the culture medium of CdCl2-exposed hepatocytes were significantly decreased, while [Ca2+]i appeared to be significantly elevated (p<0.05 or p<0.01 vs. control). We found that in Ca2+-containing hydroxyethyl piperazine ethanesulfonic acid-buffered salt solution (HBSS) only, CdCl2 elicited [Ca2+]i increases, which comprised an initially slow ascent and a strong elevated phase. However, in Ca2+-containing HBSS with addition of 2-aminoethoxydiphenyl borane (2-APB), CdCl2 caused a mild [Ca 2+] i elevation in the absence of an initial rise phase. Removal of extracellular Ca2+ showed that CdCl2 induced an initially slow [Ca2+]i rise alone without being followed by a markedly elevated phase, but in a Ca2+-free HBSS with addition of 2-APB, CdCl2 failed to elicit the [Ca2+]i elevation. These results suggest that abnormal Ca2+ homeostasis due to cadmium may be an important mechanism of the development of the toxic effect in murine hepatocytes. [Ca2+]i elevation in acutely cadmium-exposed hepatocytes is closely related to the extracellular Ca2+ entry and an excessive release of Ca2+ from intracellular stores., S. S. Wang, L. Chen, S. K. Xia., and Obsahuje bibliografii a bibliografické odkazy
The ubiquitin-proteasome pathway fulfills major biological functions, but its physiologic tissue distribution and the interrelationship between pathway component activities and ubiquitin pools are unknown. Therefore, we analyzed free and conjugated ubiquitin, ubiquitin-protein ligation rates (UbPL) and chymotryptic- and tryptic-like proteasome peptidase activities in porcine skeletal muscle, heart, lung, liver, spleen and kidney (n=5 each). There were considerable differences between tissues (p<0.05 for all parameters). Lung and spleen showed high levels of free and conjugated ubiquitin and high UbPL. Proteasome activities were highest in kidney and heart. There were linear relationships between tryptic-like and chymotryptic-like proteasome peptidase activities (r2 = 0.624, p<0.001) and between free and conjugated ubiquitin tissue levels (r2 = 0.623, p<0.001). Tissue levels of free and conjugated ubiquitin correlated linear with UbPL (p<0.005), but they were not correlated with proteasome peptidase activities. The results suggest that tissue ubiquitin pools are tightly regulated and indicate a constant proportion of conjugated ubiquitin. They further support the hypothesis that ubiquitin-protein ligase systems, and probably deubiquitylating enzymes, are key regulators of ubiquitin homeostasis. The detected differences are suggestive of tissue-specific roles of ubiquitin-proteasome pathway components. Besides the known importance of the ubiquitin proteasome pathway in heart, kidney and the immune system, the results suggest the lung as another organ in which ubiquitin proteasome pathway components may also significantly contribute to disease processes., M. B. Patel, M. Majetschak., and Obsahuje bibliografii a bibliografické odkazy
In this study, we questioned whether ground-level ozone (O3) induces hormesis in Japanese larch (Larix kaempferi) and its hybrid F1 (L. gmelinii var. japonica × L. kaempferi). In order to answer the question, we exposed seedlings of both taxa to four O3 treatments [ranging from ≈10 to 60 nmol(O3) mol-1] in open-top chambers for two consecutive growing seasons. We found a hormetic response in maximum photosynthetic rate (PNmax) at 1700 μmol(CO2) mol-1 and maximum rates of carboxylation (Vcmax) and electron transport (Jmax) in both larches. Stimulation of PNmax, Vcmax, and Jmax did not lead to suppressed plant productivity in Japanese larch, which followed a stress-tolerant strategy, but it did lead to suppressed plant productivity in hybrid larch which followed a competitive strategy. These findings are the first to suggest that stimulation of physiological functions by low O3 exposures may have negative consequences for larch reproduction., T. Sugai, D.-G. Kam, E. Agathokleous, M. Watanabe, K. Kita, T. Koike., and Obsahuje bibliografii
Appeals of philosophers to look for new concepts in sciences are being met with a weak response. Limited attention is paid to the relation between synthetic and analytic approach in solving problems of biology. An attempt is presented to open a discussion on a possible role of holism. The term “life manifestations” is used in accordance with phenomenology. Multicellular creatures maintain milieu intérieur to keep an aqueous milieu intracellulair in order to transform the energy of nutrients into the form utilizable for driving cellular life manifestations. Milieu intérieur enables to integrate this kind of manifestations into life manifestations of the whole multicellular creatures. The integration depends on a uniqueness and uniformity of the genome of cells, on their mutual recognition and adherence. The processes of ontogenetic development represent the natural mode of integration of cellular life manifestations. Functional systems of multicellular creatures are being established by organization of integrable cells using a wide range of developmental processes. Starting from the zygote division the new being displays all properties of a whole creature, although its life manifestations vary. Therefore, the whole organism is not only more than its parts, as supposed by holism, but also more than developmental stages of its life manifestations. Implicitly, the units of whole multicellular creature are rather molecular and developmental events than the cells per se. Holism, taking in mind the existence of molecular and space-time biology, could become a guide in looking for a new mode of the combination of analytical and synthetic reasoning in biology., J. Křeček., and Obsahuje bibliografii a bibliografické odkazy
Climate change impacts environmental conditions that affect photosynthesis. This review examines the effect of combinations of elevated atmospheric CO2, long photoperiods, and/or unfavorable nitrogen supply. Under moderate stress, perturbed plant source-sink ratio and redox state can be rebalanced but may result in reduced foliar protein content in C3 plants and a higher carbon-to-nitrogen ratio of plant biomass. More severe environmental conditions can trigger pronounced photosynthetic downregulation and impair growth. We comprehensively evaluate available evidence that microbial partners may be able to support plant productivity under challenging environmental conditions by providing (1) nutrients, (2) an additional carbohydrate sink, and (3) regulators of plant metabolism, especially plant redox state. In evaluating the latter mechanism, we note parallels to metabolic control in photosymbioses and microbial regulation of human redox biology.
The reactions of human organism to changes of internal or external environment termed as stress response have been at the center of interest during recent decades. Several theories were designed to describe the regulatory mechanisms which maintain the stability of vital physiological functions under conditions of threat or other environmental challenges. However, most of the models of stress reactivity were focused on specific aspects of the regulatory outcomes - physiological (e.g. neuroendocrine), psychological or behavioral regulation. Recently, a novel complex theory based on evolutionary and developmental biology has been introduced. The Adaptive Calibration Model of stress response employs a broad range of the findings from previous theories of stress and analyzes the responsivity to stress with respect to interindividual differences as a consequence of conditional adaptation - the ability to modify developmental trajectory to match the conditions of the social and physical environment. This review summarizes the contributions of the most important models in the field of stress response and emphasizes the importance of complex analysis of the psycho-physiological mechanisms. Moreover, it outlines the implications for nonpharmacological treatment of stress-related disorders with the application of biofeedback training as a promising tool based on voluntary modification of neurophysiological functions., I. Tonhajzerova, M. Mestanik., and Obsahuje bibliografii
Cold-season beetles, Catops nigricans Spence, Choleva agilis Illiger and Choleva elongata Payk., i.e. beetles which start to lay eggs in autumn, which are active during the winter in the adult stage and develop from the egg stage to the adult stage mainly during the winter months, were collected from various locations in north-western Europe and reared in the laboratory at varying temperatures and photoperiods.
Reproduction of all species started in autumn and continued during the winter months. Highest reproductive and survival rates occurred at low temperatures and within a small thermal window ranging from 5° to 10°C: The fitness of individuals decreased at higher and lower temperatures. The lower thermal threshold for all developmental stages was in the range from -5°C to +2°C. The metabolisms of the species were independent of temperature in both dormant and non-dormant stages and were elevated in the low temperature range in comparison to other species which show a temperature-dependent reaction pattern.
Optimal dates for reproduction were determined by the duration of an obligatory adult summer diapause. In C. nigricans, which favours the litter layer of deciduous forests, this duration was fine-tuned by exogenic factors, such as photoperiod and temperature. In contrast, the soil-inhabiting species Ch. elongata showed a homeostatic response pattern, independent of temperature and photoperiod. Heritability (h2) of the duration of diapause was approximately 0.26 in C. nigricans, less pronounced in Ch. agilis (ca. 0.12) and not evident in the subterranean species Ch. elongata.
All three species compensated for the vagaries of climate through bet-hedging tactics. Bet-hedging is so pervasive that a recent substantial increase in temperature seems to have a negligible effect on the distribution pattern of all three species. Based on life-history data it is conceivable that both soil-inhabiting Choleva species, which require a relatively low thermal sum for their development, were already present in western Europe during the sub-arctic conditions when ice shields reached their maximum extension during glacial periods by shifting their activity from the cold to the warm season. The Atlantic fringe north of the Pyrenees, where the climate was not cold enough for permafrost during glacial stages, was probably the only refuge where Ch. elongata might have survived. In contrast, the Mediterranean region should have been the northernmost refuge for C. nigricans during glacial periods. This species has relatively high day-degree requirements (= 1150 d°) for individual development when compared to both Choleva species (= 700 d°).
Tuková tkáň je endokrinní orgán produkující početné cytokiny. Změna v jejich regulacích může být příčinou patologických pochodů u obézních jedinců. Význam tukové tkáně ve vztahu k diabetu a ateroskleróze je intenzivně studován., Adipose tissue is an endocrine organ that produces numerous cytokines. Their dysregulations cause morbidity in obese individuals. The importance of this tissue in relation to diabetes and atherosclerosis is the subject of intense research., and Ilja Trebichavský, Petr Šíma.